Rods are structures usually used by engineers to keep two elements apart a determined distance (fixed or variable) carrying the loads between them. Metallic rods and struts are the main elements of many designs: they support structural or system elements and ensure even load distribution within structures. Usually, the connected structures are equipped with ball bearings to avoid the transmission of moment loads.
As an example, only on the Airbus A380 more than 300 different rods are used. Among these, of relevant importance are the rods connecting the Main Landing Gear Doors (MLGD) fittings to the fuselage structure. Being these doors critical structures, the connecting path, including the doors, are submitted to additional safety requirements. In addition, the supported loads of the rods are the cyclic loads of each opening/close of the door on each landing and take-off operation, and therefore the fatigue loads are critical. Besides, the MLGD and the Belly Fairing are identified as high risk of lightning strike. This includes all conductive parts or assemblies which form the aircraft skin or outside surfaces. For that reason, the doors must be electrically grounded to the main structure. As the connection of the doors with the fuselage is through the fittings and the rods, the rods must be able to transfer the required current. This is currently done through copper bonding jumpers, attached to the rods by means of metallic clamps.
The main technical problem is that the current rods are very heavy for the purposes described. Besides, there is a problem to be solved regarding the manufacturing method which currently is made by screwing together the complex two metallic bodies once they have been manufactured independently.